Method and apparatus for cleaning coal



March 31. 1925. 1,531,374

R. B. BLACKBURN ET AL METHOD AND APPARATUS FOR CLEANING COAL Filed June 1 6, 1921 2 Sheets-Sheet 1 FIG. 1

March 31, 1925.

1,531,374 R.B.BLACKBURN ETAL METHOD AND APPARATUS FOR CLEANING COAL Filed June 16, 1921 2 Sheets-Sheet 2 I I I: I I A; H I y 2/ FIG. 2 16 U C ;r I X A I, l

1/ B 2 0 VJ Patented Mar. 31, 1925.

STATES PATENT QFEHCJE.

ROBERT B. BLACKBURN, F GLAssPeR'r, rsicusamvaum, AND GQUVE-RNEUR s. :saowu, or HINSDA-L'E, ew HAMPSHIRE.

METHOD AND ABiEAR-ATUS F03 CLEANING COAL.

Application filed June 16, 1321.

To all QIJIOIIL it may concern:

Be it known that we, ROBERT 13. BLACK- BURN and Gouvassuuu BRowN, citizens of the United States, and residents of Glasspei't and Hinsdale, respectively, in the counties of Alleghen and Cheshire, respective y, and States ofPennsylva nia and New Hampshire, respectively, have invented a new and useful Improvement in Methods.

and Apparatus for Cleaning Coal; and we do hereby declare the following to be a full, clear, and exact description thereof.

@ur invention relates to the separation of coal from slate other impurities.

When coal is originally mined it contains a considerable amount of bone and slate, and sometimes considerable quantities of pyrites and other mineral impurities. This makes it necessary to clean the coal before it is used, which is usually accomplished either by hand picking or by washing. Both of these methods of separating the coal from the impurities are expensive, and it s our primary object to dispense with both of these ordinary separating methods and to clean the coal quickly a satisfactory manner without the use of manual labor or com- 'plicated' washing machinery.

More specifically, it is our object to sepa 30 rate coal from; its impurities by means of centrifugal force, the coal being delivered upon a rotary separator which, by reason of the difiierent specific gravities of the coal and the slate, and also by reason of their differences surface friction, throws out the coal and the slate at .difierent points and in difierent directions which are singularly displaced sufiicieiutly to enable the coal and slate to be separately collected. The separator may take various forms, but we prefer at present to employ a bowl-shaped separator rotating on. vertical axis.

A further object of our invention is to u'ovide effective means for delivering the coal to the rotating separator in such a way that every lump reaches the surface of the separator at substantially the same point, so that every lump, both of coal and slate, is subjected to substantially the same amount of centrifugal force.

In the accompanyin, drawings, Fig. l is a vertical sectional View showing one dorm of apparatus constructed in accordance with our invention; Fig. 2 is a plan view of the constructio shown in F g. 1; and. Figs. 3

Serial No. 478,293.

and 4 are vertical sectional views showing modified forms of separatinq bowls.

Referring to the drawings, the numeral 2 designates a rotary bowl which is mounted at the top of a spindle 3 that is vertically mounted in a frame 4, a lower bearing; 5 and an upper roller bearing 6 being provided to support the spindle 3 and insure its proper rotation. For rotating the bowl 2 a conventional form of drive is shown in Fig. 1, consisting of an el ctric motor 7, gears 8 and 9, a cmlntershaft 10, and a bevel gear 11 carried by the shaft and meshing with a bevel gear 12- carried by the vertical spindle This form of drive is shown for the purpose .of illustration only, and may be replaced by any other desired form of drive, either direct or through pulleys and belts Or the like, the onlyrequirelnent being that the bowl 2 be rotated at constant speed, which speed, however, is preferably controllable to provide for handling a greater or less auiouut of material.

The coal to be cleauedis introduced into the bowl 2 through a hopper 15 and a chute 1.6, suitable means being provided, if desired, to feed the material to the chute at a constant rate. In order that all of the lumps of coal and slate may be subjected to substaaltiaxlly the same amount of centrifugal force in substantially the same manner, it is necessary that the movement of the individual lumps of material be so controlled that they are brought tothe same angular position on the tuner surface of the bowl at the time when they are released from. the chute and brought under the free action of the bowl. One of the several ways for ac- .compilz islsiing this is shown in Figs. 1 and 2, Where the chute 1 .6 is provided at its lower end with a. vane 17 which extends obliquely across the mid of the chute. The bowl 2,

showu in Fig. .2, rotates in a counterclockwise direction, and therefore the lumps of material, when they reach the lower end of the chute and come into contact with the bowl, are over against the vane 17 and are .cnowded around the outer end of the wane 17 by the combined. force of the rotatiln-g Ehowl and the pressure of the material descending in the chute. The efiect of this action is that the individual lumps of material are delivered from the outer end of the vane 17 substantially one by one. although th y follow each other with great rapidity. In this way each individual lump is acted upon independently by the rotating bowl and the lumps of coal follow an upward and outward spiral path such as that indicated, for example, by the dotted line marked coal on Fig. 2. The lumps of slate or other heavy impurities follow another spiral line which is above the line traversed by the lumps of coal, this difference in direction resulting from the greater specific gravity of the slate and also from its greater friction, which causes the lumps of slate to hug the side of the bowl more closely than the lumps of coal. The slate, consequently, follows a line of somewhat the shape shown by the dotted line marked slate on Fig. 2.

The dotted lines showing the directions of movement of the coal and the slate illustrate substantially what happens when our invention is applied to the treatment of bituminous coal from the Pittsburgh seam by means of one type of bowl which we have used. It will be seen that the coal and the slate leave the periphery of the bowl 2 in directions which diverge at substantially 90. Therefore, in order to effectively separate the coal from the slate it is only necessary to provide suitable means for separately collecting the material which is thrown from the bowl 2. Such collecting means may be arranged in various ways and are indicated somewhat diagrammatically by vertical walls 20 and 21. Suitable receiving hoppers and chutes (not shown) are provided beneath and to the right of the walls 20 and 21.

It is not to be understood that all of the lumps of coal and slate follow each other in exact single file along the lines shown on the drawing. There is a small amount of variation caused by slight differences in the specific gravity of the lumps, and the practical result is that more or less material flies from the bowl at practically all'points between the points A and B where the coal line and the slate line across the periphery of the bowl. Most of the slate flies out of the bowl in the neighborhood of the point B, and most of-the coal flies out in the neighborhood of the point A. The

. material which flies out between these points contains both slate and coal, the amount of: coal increasing toward the point A and the amount of slat increasing toward the point B. 'llhcrefore, we prefer to make the partition wall 21 adjustable toward and from the wall 20, so that the partition 21 can be placed at various points between the points A and B, thus permitting the selection of the amount of slate that is retained with the coal. For some purposes it is necessary that the slate be removed as completely as possible, in which case the partition 21 is brought close to the point A. In other cases it is permissible to leave a certain amount of slate in the coal, and in such cases the partition 21 is moved further to the right, thus catching part of the slate with the coal. The angular adjustment of the partitions 20 and 21 around the periphery of the bowl is indicated by double arrows C on Fig. 2.

The exact design of the bowl 2 may be considerably varied. In the form shown in Fig. 1 the bowl 2 is of parabolic curvature. Fig. 3 shows a bowl 2 which is circularly curved, and Fig. 4 shows a bowl 2 in which the sides are straight. All of these forms are suitable for use in practicing our invention. The exact height and slope of the sides of the bowl depend upon the nature of the coal to be treated. The shape shown in Fig. 1 is suitable for use in treating coal from the Pittsburgh seam where there is a considerable difference between the specific gravity of the coal and the specific gravity of the slate. For treating coal where there is less difference between the specific gravities of the coal and the impurities, the sides of the bowl should be made steeper and higher, in order that the material may be kept in contact with the sides of the bowl for a longer period, thereby increasing the angle at which they diverge when leaving the bowl. On the other hand, when treating coal where this is greater difference bebetween the specific gravities of the coal and the impurities than in coal from the Pittsburgh scam, the sides of the bowl may be given a less steep inclination.

In the operation of the apparatus described above, the coal is delivered through the chute 16, and at the lower end of the chute it is directed, by means of the vane 17 or otherwise, so that all of the lumps are delivered to the bowl at practically the same point. The direction and inclination of the chute 16 are preferably such that the coal, when it reaches the inner surface of the bowl, is moving in substantially the same direction as that portion of the bowl, so that it is picked up immediately and carried on at high Velocity and under the influence of the centrifugal force set up by the rapid rotation of the bowl. The upward and outward inclination of the bowl. causes the lumps not only to rotate with the bowl, but also to rise until they reach the upper edge of the bowl, when they are thrown oil tangentially. The lumps of slate or other heavy impurities, being heavier than the coal, and also having a greater surface friction, reach the top of the bowl more quickly than the lumps of coal. The coal, on the other hand, being lighter than the slate, is acted upon more slowly by centrifugal force, and in addition, tends to bounce more or less upon the surface of the bowl, a portion of the centrifugal effect being lost at. each bounce. Therefore the coal is carried considerably farther around the bowl before it reaches the upper edge and consequently there is a marked diference between the points at which the coal and the slate are delivered.

it the coal contains pyrites, the specific ;2'i';i\'ity of which is greater than that of either the coal or the slate. the pyrites leaves the bowl before the slate and may be collected separately or not. as may be desired.

When the slate is thrown from the bowl 3 it strikes against the partition 21 and falls into a receiving hopper, not shown. The coal likOV-filse strikes against the wall 20 and falls into a receiving hopper or other suitable collecting means.

The size and shape of the lumps of coal and slate are of no importance, and we can treat material of any size down to the fineness of slack, without grading or other preliminary treatment. However, when the coal to be treated is mixed with a considerable amount of dust, such will float in the air, we prefer to screen the coal before feeding it to the centrifugal separator, in order that the dust may not interfere with the normal movement of the coal and the slate.

In erecting our apparatus, the only point where special accuracy is required, aside from producing even rotation of the bowl, is the point where the coal is delivered from the chute 16 to the bowl At this point care should be taken that the chute is in proper alignment with respect to the direction of rotation of the bowl, and also that the ane 17 is properly arranged to cause the lumps to be delivered at the same point on the bowl.

The coal and the slate are thrown from our centrifugal separator at different velocities, and this fact may be utilized in collecting the coal and slate, since the slate will be thrown farther than the coal if both are allowed to fall freely. But this method of separation, on the basis of the different distances to which the materials are thrown, will not operate. properly unless the material is lirst graded so as to furnish lumps of Jproximately the same size. For these reasons, we prefer at. present to use a bowlshaped separator. and to collect the coal and slate through their diverging directions of nnnenient. rather than through their different velocities. lt is to be understood, however. that our invention includes the use of any form of centrifugal separator, whether flat or dished to any required extent, as well as any desired method or means for collecting the centrifugally separated materials.

It will thus be evident that the principles of our invention may be put into practice in various ways, and that the details of construetion may be variously moditied in accordance with particular requirements, or in accordance with the materials that are to be treated. 'e therefore desire that no limitations be imposed on our invention except such as are indicated in the appended claims.

\Ve claim as our invention:

1. The method of cleaning coal that con1- prises introducing the coal to be cleaned into a rotating bowl eccentri -ally with re spect to the axis of rotation of said bowl and separately collecting the coal and the impurities at angularly displaced points around the periphery of said bowl.

2. The method of cleaning coal that comprises introducing the coal to be cleaned at substantially a single angular point on the interior surface of a rotating bowl eccentrically with respect to the axis of rotation of said bowl, and separately collecting the coal and the impurities at different angular points around the periphery of said bowl.

3. The method of cleaning coal that comprises introducing the coal to be cleaned into a rotating bowl, controlling the movement of the introduced material so as to release the individual lumps of said material at substantially the same angular point on the inner surface of said bowl and separate ly collecting the coal and the impurities at difl'erent points around the periphery of said bowl.

4. Apparatus for cleaning coal comprising a rotatable bowl and means for introducing the coal to be cleaned into the interior of said bowl eccentrically with respect to the axis of rotation of said bowl.

5. Apparatus for,cleaning coal comprising a rotatable bowl, and means for introducing the coal to be cleaned at substantially the same angular point on the inner surface and eccentrically with respect to the axis of rotation of said bowl.

6. Apparatus for cleaning coal comprising a rotatable bowl, means for introducing the coal to be cleaned at substantiallv the same angular point on the inner surface of paid bowl, and means for separately collecting the coal and impurities at different angular points around the periphery ofl said bowl.

7. .'\pparatus for cleaning coal comprising a rotatable bowl. and a chute extending into said bowl and terminating near the inner surface thereof and eccentricallv with respect to the axis of rotation of said bowl.

3. Apparatus for cleaning coal coinprising a rotatable bowl having curved walls, a chute extending into the said bowl and teri'ninating near the inner surface thereof. and a vane extending from one side of said chute diagonally across the open end thereof.

9. Apparatus for cleaning coal comprising a rotatable bowl having curved walls, means for introducing the coal to be cleaned lei) l'lO

into the interior of said bowl ecrentrically with respect to the axis of rotation of said bow], and means disposed adjacent to the periphery of said bowl for receiving the material issuing therefrom.

10. Apparatus for cleaning coal comprising a rotatable bowl, means for introducing the coal to be cleaned into the interior of said bowl, and walls extending radially adjacent to the periphery of said bowl for receiving the material issuing therefrom, at least one of the said walls being adjustable around the periphery of said bowl.

11. Apparatus for cleaning coal comprising a rotatable bowl, means for introducing the coal to be cleaned into the interior of said bowl, and walls extending radially adjacent to the periphery of said bowl for receiving the material issuing therefrom.

In testimony whereof, I the said ROBERT 20 B. BLACKBURN have hereunto set my hand.

ROBERT B. BLACKBURN. Witnesses:

R. D. BROWN, JOHN F. WILL. In testimony whereof, I the said Gouvnn- NEUR G. BROWN have hereunto set my hand.

GOUVERN EUR G. BROWN. Witness:

E. K. FREESE. 

